7. Project Summary / Abstract This K01 Career Development Award will provide Dr. Marily Oppezzo with intensive, supervised training to establish an independent research scientist career focusing on cardiovascular disease prevention, more specifically on how to change people?s physical activity levels for heart health. This proposal builds on Dr. Oppezzo?s background as an experimentalist trained in psychological theories of learning and behavior change, and leverages the exceptional environment of Stanford University for advanced training. Under the mentorship of her team of experts, Dr. Oppezzo will advance the field of behavior change with a novel intervention to decrease sedentary behavior, and contribute to the findings of sedentary behavior?s effects on cardiovascular health. Prolonged sitting is an independent risk factor for cardiovascular disease. The health effects of too much sitting are physiologically distinct from those of too little aerobic exercise. There is growing evidence that heart disease risk from prolonged sedentary behavior can be mitigated by breaking up sitting hours and moving more frequently throughout the day. This K01 proposal utilizes technology to both: 1. decrease sedentary behavior and 2. track cardiovascular effects of sedentary behavior. 1. Through a randomized controlled trial, Dr. Oppezzo will test the effectiveness of a multicomponent social media-based intervention (Tweet4Wellness) on decreasing prolonged sedentary behavior by increasing walking bouts throughout the day. Within a private social media group, for 100 days, participants will be prompted with daily, theory-based behavior change strategies to elicit social support and interaction around their sedentary behavior goals. 2. Using collected data from non-invasive, wrist-worn wireless biosensors, real-world patterns of sedentary behavior will be associated with patterns of blood pressure and heart rate variability. This data will not only contribute to what is known about cardiovascular biomarkers and sedentary behavior, but also detect cardiovascular effects of changing sedentary behavior over time. Training to conduct the proposed K01 will address prior gaps in Dr. Oppezzo?s knowledge and skills needed to achieve her long term goal of being an independent scientist: 1) clinical trial implementation and biosensor ?big data? processing and analysis (e.g. accelerometer, blood pressure, and heart rate variability monitoring data); 2) social media and health technology for behavioral interventions; 3) career development skills such as grantsmanship and manuscript publications. Through coursework, hands-on experience, and mentored training, Dr. Oppezzo will gain a conceptual and technical foundation to develop and test effective behavioral interventions for heart health. Results from the proposed project will directly inform an R01 application that will build on the successful features of the Tweet4Wellness intervention, refine less successful features, and run a larger, scaled clinical trial in patients with existing heart disease. In summary, this K01 will accelerate Dr. Oppezzo?s career development and support launching her as an independent behavioral scientist in cardiovascular disease prevention.